In this lecture results of the investigation of plasma electrolytic oxidation
(PEO) process on some metals (aluminum, titanium, tantalum, magnesium, and
zirconium) were presented. Whole process involves anodizing metals above the
dielectric breakdown voltage where numerous micro-discharges are generated
continuously over the coating surface. For the characterization of PEO
process optical emission spectroscopy and real-time imaging were used. These
investigations enabled the determination of electron temperature, electron
number density, spatial density of micro-discharges, the active surface
covered by micro-discharges, and dimensional distribution of micro-discharges
at various stages of PEO process. Special attention was focused on the
results of the study of the morphology, chemical, and phase composition of
oxide layers obtained by PEO process on aluminum, tantalum, and titanium in
electrolytes containing tungsten. Physicochemical methodes: atomic force
microscopy (AFM), scanning electron microscopy (SEM-EDS), x-ray diffraction
(XRD), x-ray photoelectron spectroscopy (XPS), and Raman spectroscopy served
as tools for examining obtained oxide coatings. Also, the application of the
obtained oxide coatings, especially the application of TiO2/WO3 coatings in
photocatalysis, were discussed.
Characterisation of porous coatings formed on titanium under AC plasma electrolytic oxidation